U.S. patent number 5,960,138 [Application Number 09/072,095] was granted by the patent office on 1999-09-28 for backplane connector.
This patent grant is currently assigned to Furukawa Electric Co., Ltd., Nippon Telegraph and Telephone Co.. Invention is credited to Shinji Nagasawa, Naoko Shimoji, Masaaki Takaya.
United States Patent |
5,960,138 |
Shimoji , et al. |
September 28, 1999 |
Backplane connector
Abstract
The backplane connector of the present invention can improve the
fitting accuracy of the optical connectors A and B at the backplane
1 side and the package 2 side respectively and protect the
backplane 1 from damages caused by being pressed against the first
housing 3 when the first housing 3 is fit in the backplane 1. In
the first housing 3 mounted floating in the backplane 1 is housed
the second housing 7 by latching and connecting the latching
projection 4 to the latching pawl 10, the backplane side optical
connector plug 14 is incorporated in the second housing 7. And, the
package side optical connector plug 23 is incorporated in the third
housing 18 of the package 2. Then, the third housing 18 is inserted
in the first housing 3, and the unlatching part 20 at the third
housing 18 side presses down the tip side slope 13 of the latching
pawl 10 to unlatch and disconnect the latching pawl 10 from the
latching projection 4. In this status, the ferrules 16 and 25 of
the backplane side and the package side optical connector plugs 14
and 23 are positioned and connected to connect the backplane 1 to
the package 2 optically.
Inventors: |
Shimoji; Naoko (Ichihara,
JP), Takaya; Masaaki (Tokyo, JP), Nagasawa;
Shinji (Tokyo, JP) |
Assignee: |
Furukawa Electric Co., Ltd.
(Tokyo, JP)
Nippon Telegraph and Telephone Co. (Tokyo,
JP)
|
Family
ID: |
15124551 |
Appl.
No.: |
09/072,095 |
Filed: |
May 4, 1998 |
Foreign Application Priority Data
|
|
|
|
|
May 8, 1997 [JP] |
|
|
9-134278 |
|
Current U.S.
Class: |
385/58; 385/53;
385/60 |
Current CPC
Class: |
G02B
6/3893 (20130101); G02B 6/3897 (20130101); G02B
6/3885 (20130101); G02B 6/3822 (20130101) |
Current International
Class: |
G02B
6/38 (20060101); G02B 006/38 () |
Field of
Search: |
;385/53,54,55,56,57,58,69,60,72 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Palmer; Phan T. H.
Attorney, Agent or Firm: Lacasse & Associates Lacasse;
Randy W. Strickland; Wesley L.
Claims
What is claimed is:
1. A backplane connector comprising a first housing mounted
floating thereon, opened at its tip, and provided with a locking
latch on its housing wall surface; a second housing inserted in
said first housing with its tip opening arranged in the same
direction as that of the tip opening of said first housing and
incorporating at least one backplane side optical connector plug;
and a third housing having a package on its outer surface, opened
at the tip, having a package side optical connector plug therein,
and having a locking pawl being fit in said first housing and to be
engaged with said locking latch at a preset fitting position,
wherein a latching projection is formed on the inner surface of
said first housing, a latching arm is formed on the outer surface
of second housing, which faces said latching projection formed
surface of said first housing, said latching arm being extended
toward the tip opening of said second housing along the outer
surface of said second housing through a clearance, and at the tip
side of said extended latching arm is provided a latching pawl
having an engaging stepped portion protruded outside, and said
latching projection of said first housing is engaged with this
engaging stepped portion to latch and connect said first housing to
said second housing, and at this latching pawl is formed a
two-shoulder stepped slope whose inclination in the axial direction
becomes larger from the base to the tip, and an unlatching part is
formed at said third housing so that said third housing is fit in
said first housing to let said unlatching part hit and come in
contact with the tip side slope of said latching pawl, then said
unlatching part presses said latching pawl down in the axial
direction to unlatch and disconnect said first housing from second
housing, and while in this unlatching status, the optical
connection is kept between said backplane side optical connector
plug and said package side optical connector plug.
2. A backplane connector as defined in claim 1, wherein said
backplane side optical connector plug and said package side optical
connector plug are positioned and connected to each other by
fitting two alignment pins in a pair of alignment holes provided on
the connecting end faces of said optical connector plugs on both
sides.
3. A backplane connector as defined in claim 2, wherein two
alignment pins are fixed to said optical connector plug at either
said backplane side or said package side, and the fixing force is
set larger than the force of reconnecting latchingly said first
housing to said second housing when said third housing is removed
from said first housing, as well as the force of unlocking and
disconnecting said third housing from said first housing.
4. A backplane connector as defined in claim 3, wherein when said
backplane connector is formed so that said alignment pins on one
end side are fit in the alignment holes of said optical connector
plug at either backplane side or package side and said alignment
pins are also fit in the alignment holes of said other optical
connector plug from the tip side from which said alignment pins are
protruded to position and connect the optical connector plugs at
said backplane side and said package side, if the fitting length of
said second housing and said third housing when the alignment pins
protruded from one of said optical connector plugs is fit in the
alignment holes of the other optical connector plug is defined as
L, the difference between the diameter of the tip of each of said
protruded alignment pins and the diameter of each of the alignment
holes in which said alignment pins are fit is defined as
.delta..phi., the clearance formed after said second housing is fit
in said third housing is defined as .delta.h, the protrusion length
of the ferrule protruded from the plug housing is defined as f, and
the protrusion length of the alignment pins protruded from the end
face of said ferrule is defined as a, then the relationship of
.delta..phi., >.delta., h/2+(.delta.h/L) (f+a) is satisfied.
5. A backplane connector as defined in claim 2, wherein when said
backplane connector is formed so that said alignment pins on one
end side are fit in the alignment holes of said optical connector
plug at either backplane side or package side and said alignment
pins are also fit in the alignment holes of said other optical
connector plug from the tip side from which said alignment pins are
protruded to position and connect the optical connector plugs at
said backplane side and said package side, if the fitting length of
said second housing and said third housing when the alignment pins
protruded from one of said optical connector plugs is fit in the
alignment holes of the other optical connector plug is defined as
L, the difference between the diameter of the tip of each of said
protruded alignment pins and the diameter of each of the alignment
holes in which said alignment pins are fit is defined as
.delta..phi., the clearance formed after said second housing is fit
in said third housing is defined as .delta.h, the protrusion length
of the ferrule protruded from the plug housing is defined as f, and
the protrusion length of the alignment pins protruded from the end
face of said ferrule is defined as a, then the relationship of
.delta..phi., >.delta.h/2+(.delta.h/L) (f+a) is satisfied.
6. A backplane connector as defined in claim 1, wherein each of
said backplane side optical connector plug and said package side
optical connector plug is being comprised of a plug housing
incorporating a ferrule that houses an optical fiber, and the
connecting end side of said ferrule is enforced by a spring and
protruded slide-ability from the tip of said plug housing, and when
the overlapping area of the engagement between said latching
projection of said first housing and said engaging stepped portion
of said latching pawl of said second housing is defined d, the
interval between plug housings at said backplane side and said
package side when said third housing is fit in said first housing
is defined as .DELTA., the base end side inclination of said
two-shoulder stepped slope of said second housing latching pawl is
defined as .theta..sub.2, and the tip side inclination is defined
as .theta..sub.1, then the relationship between .theta..sub.1 and
.theta..sub.2 is assumed to be 0<.theta..sub.2 <arc tan
(d/.DELTA.)<.theta..sub.1 <90.degree..
Description
FIELD OF THE INVENTION
The present invention relates to a backplane connector for
connecting a package optically to a unit provided on the backplane
side, for forming, for example, a communication cabinet, as a
book-shelf type connection.
BACKGROUND OF THE INVENTION
In recent years, there have developed technologies of connecting a
package being comprised of optical and electronic parts thereon to
a backplane side unit comprised of optical and electric circuits
formed thereon using a communication cabinet respectively. For
example, one such technology, which connects a package to a
backplane side unit using a single-fiber optical connector, is
disclosed in Japanese Laid-Open Patent Publication No. 164704 of
1991.
OBJECT AND SUMMARY OF THE INVENTION
In recent years, however, a higher-fiber packing density has
required more and more units and packages of communication
cabinets. In order to meet such a requirement, an optical
connection technology is needed to connect a package to a backplane
side unit using a multi-fiber optical connector. And furthermore,
the development of a backplane connector usable for connecting each
of the prior art single-fiber optical connectors is also
required.
In the case of each type of backplane connector, the optical
connector attached to a package is connected to the connector
attached to the object backplane side unit to realize an optical
connection between the package and the backplane unit, but the
aligning accuracy depends significantly on various factors such as
errors in fixing packages and optical connectors, errors in fixing
backplanes to optical connectors, the manufacturing errors of
optical connectors used on both packages and backplanes, the errors
of fitting parts on both optical connectors, etc. And, thus far
there have been no backplane connectors provided that can solve the
above errors satisfactorily.
Under such circumstances, it is an object of the present invention
to solve the above problems and provide a backplane connector that
allows a high packing density of parts to be mounted thereon and to
be compacted significantly in size with excellent connection
accuracy.
In order to achieve the above object, the present invention takes
the following measures. They are; the backplane connector in an
embodiment of the present invention comprises the first housing
mounted floating on a backplane, opened at its tip, and having a
locking latch on its wall surface; the second housing inserted in
the first housing so that its tip opening is aligned to the tip
opening of the first housing in the same direction and
incorporating at least one backplane side optical connector plug;
and the third housing having a package on its outside surface,
being opened at its tip, incorporating a package side optical
connector plug in itself, and having a locking pawl fit in the
first housing and to be latched by the locking latch at a preset
position. And, a latching projection is formed on the inner surface
of the first housing. On the outer surface of the second housing,
facing the latching projection-formed surface of the first housing,
is formed a latching arm extended through a clearance toward the
tip opening of the second housing along the outer surface of the
second housing, and at the tip of the extended latching arm is
provided a latching pawl having an engaging stepped portion, and
protruded outside. The latching projection is engaged with this
engaging stepped portion to latch and connect the first housing to
the second housing. At this latching pawl is formed a two-shoulder
stepped slope so that the inclination of the stepped portion
becomes larger in the axial direction from the package side to the
tip side. The third housing is provided with an unlatching part.
When the third housing is fit in the first housing, the unlatching
part comes into contact with the slope formed at the tip of the
latching pawl so as to press the latching pawl down in the axial
direction to unlatch the connection between the first housing and
the second housing. While the first and second housings are
disconnected in such a way, the optical connection between the
backplane side optical connector plug and the package side optical
connector plug is maintained. Thus, according to the first
embodiment, the above prior art problems can be solved.
According to the second embodiment which takes the configuration of
the first invention, two alignment pins are fit in a pair of
alignment holes provided at the connecting end faces of the optical
connector plugs provided on both sides to position and connect the
backplane side optical connector plug and the package side optical
connector plug respectively and solve the above problems.
According to the third embodiment which takes the configuration of
the first embodiment each of the backplane side optical connector
plugs and the package side optical connector plugs incorporates a
ferrule having an optical fiber in its plug housing. The connecting
end of the ferrule is pressed by a spring and protruded
slide-ability from the tip of the plug housing. And, if d is
defined as the overlapping area of the latched engagement between
the latching projection of the first housing and the engaging
stepped portion of the latching pawl of the second housing, .DELTA.
is defined as the interval between the plug housings at the
backplane side and the package side when the third housing is fit
in the first housing, .theta..sub.2 is defined as the inclination
of the 2-shoulder stepped slope of the latching pawl of the second
housing on the package side, and .theta..sub.1 is defined as the
inclination on the same portion on the tip side, then the
relationship between .theta..sub.1 and .theta..sub.2 becomes
0<.theta..sub.2 <arc tan (d/.DELTA.)<.theta..sub.1
<90.degree.. Thus, according to the second embodiment the above
problems can be solved.
Furthermore, according to the fourth embodiment which takes the
configuration of the second embodiment two alignment pins are fixed
to the optical connector plug at either the backplane side or the
package side, and the fixing force is set larger than the
disconnecting force for the latched connection between the first
housing and the second housing when the third housing is removed
from the first housing and the force needed to unlock and remove
the third housing from the first housing. Thus, according to the
fourth embodiment, the above problems can be solved.
Furthermore, according to the fifth embodiment which takes the same
configuration as that of the second or fourth embodiment and solves
the above problems as follows; when the alignment pins provided on
one side are fit in the alignment holes of the optical connector
plug of either the backplane or the package and the protruded tips
of the alignment pins are fit in the alignment holes of the other
optical connector plug to position and connect the optical
connector plugs at both the backplane side and the package side,
then the relationship of
.delta..phi.>.delta.h/2+(.delta.h/L).times.(f+a) is satisfied if
L is defined as the fitting length between the second housing and
the third housing when the alignment pins protruded from one
optical connector plug are fit in the alignment holes of the other
optical connector plug, .delta..phi. is defined as the difference
in the diameter of the tip of each protruded alignment pin from the
diameter in each alignment hole in which an alignment pin is fit,
.delta.h is defined as the fitting clearance between the second
housing and the third housing, f is defined as the protrusion
length of the ferrule protruded from the plug housing, and a is
defined as the protrusion length of each alignment pin protruded
from the end face of the ferrule.
In the present invention, when the third housing is fit in the
first housing by holding the package, the third housing is fit in
the first housing, and then in the second housing.
When the third housing is further inserted deeply as described
above, the connecting end faces of the optical connector plugs at
both the backplane side and the package side, that are, the
connecting end faces of the ferrules, are pressed to come in
contact with each other. And, at this time, the locking pawl goes
beyond the locking portion to be latched at the locking portion. On
the other hand, the unlatching part of the third housing comes in
contact with the larger inclination angle slope formed at the tip
of the latching pawl of the second housing to press the latching
pawl down in the axial direction. When the latching pawl is pressed
down in such a way, the latching projection of the first housing is
released from the engaging stepped portion of the latching pawl, so
that the latched connection between the first housing and the
second housing is released, and accordingly, the optical connection
between the optical connector plugs at both the backplane side and
the package side is kept while the latched connection between the
first and second housings are unlatched.
When disconnecting the backplane connector, the package is held by
hand to give a pulling-out force to the first housing. With this
given pulling-out force, the unlatching part of the third housing
is separated from the latching pawl, so that the latching pawl is
returned to its initial position from its pressed-down position by
an elastic force. Consequently, the engaging stepped portion of the
latching pawl is engaged with the latching projection of the first
housing, and the first housing is connected and latched to the
second housing. Furthermore, when the third housing is pulled out
and moved, the locking pawl of the third housing is released from
the locking latch of the first housing, and accordingly, the first
housing is unlocked from the third housing so that the third
housing is removed from the first housing and the optical
connection is disconnected from the backplane connector.
According to the present invention, when the package side third
housing is fit in the first and second housings on the backplane
side, the unlatching part of the third housing is used to unlatch
the latching pawl of the second housing and disconnect the first
housing from the second housing. Thus, after the disconnection, the
first housing is free and even when the third housing is further
inserted, the inserting force does not affect the backplane via the
first housing. And accordingly, the present invention can prevent
the characteristics of the optical and electric circuits on the
backplane completely from degradation caused by the first housing
pressed against the backplane.
Furthermore, since the slope provided on the outer surface of the
latching pawl of the second housing is formed as a two-shoulder
stepped portion being comprised of the package side slope and the
tip side slope, as well as the inclination of the tip side slope is
set larger than the inclination of the package side slope. Thus,
the first housing can be unlatched from the second housing with a
less pushing-in length after the unlatching part of the third
housing comes in contact with the tip side slope. As a result, the
fitting length of the second and third housings can be reduced
according to the reduction of the pushing-in length. In addition,
the backplane connector can be reduced in size significantly.
Moreover, since the inclination of the slope of the latching pawl
on the package side is set smaller than that of the slope on the
tip side, the force of reconnecting the first housing to the second
housing can be reduced when the package side latching pawl is
pulled out to remove the third housing from the first and second
housings. And, the force of pulling the third housing out can be
reduced according to the reduction of the reconnecting force so
that the third housing is pulled out smoothly.
Furthermore, if, when d is defined as the overlapping area of the
engagement between the latching projection of the first housing and
the engaging stepped portion of the latching pawl of the second
housing, the third housing is fit in the first housing, that is,
when .DELTA. is defined as the interval between the plug housings
at the backplane side and the package side when the unlatching part
of the third housing comes in contact with the tip side slope of
the latching pawl of the second housing, then the relationship
between the inclination .theta..sub.1 of the tip side slope of the
latching pawl of the second housing and the inclination
.theta..sub.2 of the package side slope is defined as
0<.theta..sub.2 <arc tan (d/.DELTA.)<.theta..sub.1
<90.degree.. Thus, it is possible to obtain an effect that the
latched connection between the first housing and the second housing
can be unlatched and disconnected completely before the backplane
side optical connector plug housing comes in contact with the
package side optical connector plug housing.
Furthermore, the relationship of
.delta..phi.>.delta.h/2+(.delta.h/L).times.(f+a) is satisfied if
L is defined as the fitting length between the second housing and
the third housing when the alignment pins protruded from one
optical connector plug are fit in the alignment holes of the other
optical connector plug, .DELTA..phi. is defined as the difference
of the diameter of the tip of each protruded alignment pin from the
diameter of each alignment hole in which an alignment pin is fit,
.delta.h is defined as the fitting clearance between the second
housing and the third housing, f is defined as the protrusion
length of the ferrule protruded from the plug housing, and a is
defined as the protrusion length of each alignment pin protruded
from the end face of the ferrule. Thus, when the backplane side
connector is engaged with the package side connector, the alignment
pins do not hit the edges of the alignment holes, so that it is
possible to prevent completely the problem of alignment pins
hitting the edges of the alignment holes and damaging the alignment
holes.
Furthermore, since the present invention sets the fixing force of
the alignment pins larger than the force for the latched
reconnection between the first and second housings when the third
housing is removed from the first housing and the force of
unlatching and removing the third housing from the first housing,
the problem with alignment pins, when the backplane connector is
disconnected, receive the disconnecting force and are pulled out
with force, can be prevented without fail.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and advantages of the present invention
will become more apparent and more readily appreciated from the
following detailed description of the exemplary embodiments of the
invention taken in conjunction with the accompanying drawings, in
which:
FIG. 1A to FIG. 1C illustrate a configuration of a backplane
connector in an embodiment of the present invention, indicating how
the first housing is unlatched from the second housing.
FIG. 2A and FIG. 2B illustrate a configuration of the backplane
connector in the above embodiment, indicating how the backplane
connector is locked and connected.
FIG. 3 illustrates a backplane side optical connector plug and a
ferrule incorporated in a package side optical connector plug.
FIG. 4 is an exemplary view of the ferrule housed in a plug
housing.
FIG. 5 illustrates a problem that the first housing cannot be
unlatched from the second housing.
FIG. 6 illustrates an interval .DELTA. between plug housings at the
beginning of latched connection therebetween in the above
embodiment.
FIG. 7 illustrates the relationship between the inclinations
.theta..sub.1, .theta..sub.2 of the two-shoulder stepped portion of
the latching pawl and the overlapping area d in the latched
connection in the above embodiment.
FIG. 8 illustrates a configuration of the tip side of the locking
pawl provided for the third housing.
FIG. 9 illustrates a problem that the latching pawl at the second
housing side cannot come in contact with the body of the second
housing so as to be latched and connected.
FIG. 10 illustrates a configuration for solving the problem shown
in FIG. 9.
FIG. 11 illustrates in detail the tip where the backplane side
optical connector plug is connected to the package side optical
connector plug.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Hereunder, a preferred embodiment of the present invention will be
described with reference to the attached drawings. FIG. 1A to FIG.
1C and FIG. 2A to FIG. 2B illustrate the major portion of the
backplane connector in an embodiment of the present invention
respectively. In each of those drawings, the backplane connector
comprises an optical connector A at the backplane 1 side and an
optical connector B at the package 2 side. On the backplane 1 are
formed electric and optical circuits. On this backplane 1 is also
mounted the first housing 3 floating. The configuration of the
floating first housing 3 is well known, for example, in Japanese
Laid-Open Patent Publication No. 164704 of 1991, etc. The first
housing 3 is floating mounted on the backplane 1 using a proper
configuration described in those patent applications.
The first housing 3 is opened at its tip. On the inner surface of
the first housing 3 is formed a latching projection 4 protruded
inside as shown in FIG. 1. On the surfaces (surfaces in the
horizontal direction in FIG. 1) orthogonal to the surfaces on which
the latching projection 4 of the first housing 3 is formed
respectively is formed a locking latch 5 respectively as shown in
FIG. 2 (represented as upper and lower faces in FIG. 2). Between
the tip side of the first housing 3 and this locking latch 5 is
provided a triangular running-on face 6 on both sides of the
locking latch 5 in the width direction (orthogonal direction in
FIG. 2) respectively.
In the first housing 3 is inserted the second housing 7
slide-ability. The second housing 7 is also opened at its tip and
this opening of the second housing 7 is aligned to the opening of
the first housing in the same direction.
As shown in FIG. 1, a latching arm 8 is formed on the outer surface
of the second housing 7, which faces the surface of the first
housing 3, on which the latching projection 4 is formed. The base
end of this latching arm 8 is connected to the second housing 7.
The latching arm 8 is extended from this base end to the tip of the
second housing 7 along the outer surface of the second housing 7
through a clearance formed between the outer surface of the second
housing 7 and the outer surface of the first housing 3, which is in
parallel to the outer surface of the second housing 7. At the tip
of this extended latching arm 8 is formed a latching pawl 10. This
latching pawl 10 is provided with an engaging stepped portion 11
protruded outside from the tip of the latching arm 8. On the outer
surface of this latching pawl 10 is formed slopes 12 and 13
inclined more as they go closer to the tip in the axial direction
of the second housing 7. The slope 12 is formed on the base end
side and the slope 13 is formed on the tip side. The inclination
.theta..sub.1 of the tip side slope 13 is larger than the
inclination .theta..sub.2 of the base end side slope 12 as shown in
FIG. 7.
A backplane side optical connector plug 14 is inserted in the
second housing 7 through a hole formed in the backplane 1.
This backplane side optical connector plug 14 has a ferrule 16
housed in a plug housing 15 slide-ability in the moving direction
on the tip side. And, as shown in FIG. 4, the ferrule 16 is pressed
by a spring 17 forward, and the ferrule 16, resisting the force of
the spring 17, can move backward in the plug housing 15.
On the outer surface of the third housing 18 is provided a package
2. This third housing 18 is opened at its tip, and as shown in FIG.
1, the third housing 18 is provided with an unlatching part 20 on
the opposite side of the latching pawl 10 provided on the second
housing 7. This unlatching part 20 is formed like a pawl having a
slope 21 to run onto the slopes 12 and 13 of the latching pawl
10.
In addition, the third housing is provided with a locking pawl 22
as shown in FIG. 2 at a position facing the locking latch 5
provided on the first housing 3. This locking pawl 22 is latchingly
engaged with the locking latch 5 at a preset fitting position with
respect to the third housing 18 and the first housing 3.
Inside the third housing 18 is incorporated a package side optical
connector plug 23. This package side optical connector plug 23,
just like the backplane side plug housing 15, houses a ferrule 25
slide-ability on the tip side of the package side plug housing 24.
And, as shown in FIG. 4, this ferrule 25 is pressed by a spring 17
forward, and the ferrule 25, resisting the force of the spring 17,
can move backward just like the ferrule 16 of the backplane side
optical connector plug 14. FIG. 3 illustrates the relationship
between the ferrule 16 of the backplane side optical connector plug
14 and the ferrule 25 of the package side optical connector plug
23. In each of the ferrules 16 and 25 are formed optical fiber
inserting holes 26 arranged at equal pitches. In these optical
fiber inserting holes 26 are inserted multi-fiber optical fiber
cores 28 such as optical fiber ribbon, etc., which are unsheathed,
so that those bare optical fibers are exposed to be made flush at
the connecting end face of each of the ferrules 16 and 25. The
ferrules 16 and 25 are adhered to each optical fiber core 28.
At the connecting end face 27 of each of the ferrules 16 and 25 is
formed a pair of alignment holes 30 so that the arranged optical
fiber group is put therebetween. One end of each alignment pin 31
is inserted in one alignment hole 30 of the ferrule 16. The base
end side alignment pins 31 are fixed by a proper means. Thus, two
alignment pins 31 are protruded forward from the connecting end
face 27 of the ferrule 16. The optical fibers of both the ferrules
16 and 25 are positioned properly to realize an optical connection,
since the alignment pins 31 are inserted in the alignment holes 30
of the ferrule 25.
Next, how to connect and disconnect the backplane connector in the
above embodiment will be described with reference to FIG. 1 and
FIG. 2. When connecting the backplane connector, the third housing
18 is fit in the first housing 3 of the object unit at the
backplane 1 side by holding the package 2 at first as shown in FIG.
1A and FIG. 2A. Since the first housing 3 is mounted floating in
the backplane 1 at this time, the first housing 3 can be moved
relatively to the backplane 1 within the floating range. And, since
the positioning error of the first housing 3 to occur with respect
to the backplane 1 and the fixing error such as positional
deviation to occur in fixing of the third housing 18 to the package
2 can be eliminated by a movement of the first housing 3 in
floating, the first housing can be fit in the third housing
properly.
Furthermore, the third housing 18 is fit in the second housing 7 by
moving the third housing 18 forward. Then, the ear part of the
locking pawl 22 shown in FIG. 8 runs onto the running-on surface 6
of the first housing 3 (see FIG. 2A). When the connection of the
backplane connector begins, the latching projection 4 of the first
housing 3 is engaged with the engaging stepped portion 11 of the
latching pawl 10 of the second housing 7 as shown in FIG. 1A, so
that the first housing 3 is latchingly connected to the second
housing 7.
When the third housing 18 is further moved forward, the alignment
pins 31 of the backplane side optical connector plug 14 are
inserted in the alignment holes 30 of the package side optical
connector plug 23 to press the ferrules 16 and 25 so that the
connecting end faces 27 of both the ferrules 16 and 25 come in
close contact with each other. At this time, the locking pawl 22
goes beyond the running-on surface 6 to be latched by the locking
latch 5. Thus, the first housing 3 is connected and locked to the
third housing 18 (see FIG. 2B).
While in this connecting, the third housing 18 is further moved
forward slightly from the state shown in FIG. 1A and the unlatching
part 20 at the third housing 18 side is in contact with the tip
side slope 13 of the latching pawl 10 at the second housing 7 side,
so that the latching pawl 10 is pressed down slightly in the axial
direction of the second housing 7 with the elastic force of the
latching arm 8.
If the third housing is moved forward in this status, the ferrules
16 and 25 are pressed into the plug housings 15 and 24 respectively
resisting the force of the spring 17 as shown in FIG. 1B. The
latching pawl 10 is further pressed down by the unlatching part 20,
so that the engaging stepped portion 11 of the latching pawl 10 is
released from the latching projection 4 of the first housing 3.
Thus, the first housing 3 is unlatched and disconnected from the
second housing 7. In this unlatching status, a clearance is formed
between the plug housings 15 and 24 at the backplane side and the
package side as shown in FIG. 1B, so both plug housings 15 and 24
are separated from each other.
When the first housing 3 is unlatched and disconnected from the
second housing 7 as shown in FIG. 1B, the first housing 3 is free
from the second housing 7, and the first housing 3 is not pressed
against the backplane 1 even when the third housing is further
moved forward slightly. FIG. 1C shows the status in which the
backplane connector is already connected. In this status, the first
housing 3 is connected to the third housing 18, since the locking
pawl 22 is locked and connected to the locking latch 5 (see FIG.
2B) as described above. The first housing 3 is unlatched and
disconnected from the second housing 7. At this time, the
connecting end face of the ferrules 16 and 25 of the backplane and
the package side optical connector plugs 14 and 23 are in
press-contact with each other. Thus, the optical fibers of the
backplane side optical connector plug 14 and the package side
optical connector plug 23 are aligned and connected optically. The
optical fiber in the backplane side optical connector plug 14 is
connected to an optical circuit on the backplane 1 and the optical
fiber in the package side optical connector plug 23 is connected to
an optical circuit of the package 2. Thus, the optical circuits on
both the backplane 1 and on the package 2 are connected optically
due to this connection of the backplane connectors.
When disconnecting the backplane connector, the package 2 is held
to remove the third housing 18. With this pulling-out force given
to the third housing 18, the third housing 18 is moved in the
pulling-out direction. At this time, since the positional
relationship between the second housing 7 and the third housing 18
is as shown in FIG. 2B, that is, since the locking latch 5 is
engaged with the locking pawl 22, the second housing 7 is moved
together with the third housing 18 in the pulling-out direction, so
that the engaging stepped portion 11 of the latching pawl 10 of the
second housing 7 can be engaged with the latching projection 4 of
the first housing 3. And, since the pressing-down force of the
unlatching part 20 against the latching pawl 10 is released at that
position, the latching pawl 10 returns to the initial position
taken before the latching pawl 10 is pressed down by the elastic
force of the latching arm 8. The engaging stepped portion 11 of the
latching pawl 10 is engaged with the latching projection 4 of the
first housing 3 as shown in FIG. 1A. And, the first housing 3 is
latched and connected to the second housing 7 again.
Furthermore, when the third housing is moved in the pulling-out
direction, the ear part of the locking pawl 22 runs onto the
running-on surface 6 in the backward direction to release the
locking pawl 22 from the locking latch 5, so that the connecting
end faces of the ferrules 16 and 25 are separated from each
other.
Furthermore, when the third housing 18 is disconnected and moved,
the alignment pins 31 are pulled out of the alignment holes 30, so
that the third housing 18 is removed completely from the first
housing 3, ending the disconnection of the backplane connector.
The features of this embodiment are as follows; when backplane
connector is to be connected, the first housing 3 can be unlatched
and disconnected from the second housing 7 completely by pressing
the third housing slightly, and when backplane connector is to be
disconnected, the first housing 3 can be latched and connected to
the second housing with a less force.
When backplane connector is to be connected, for example, when the
third housing is pushed in the connecting direction as shown in
FIG. 5, the third housing 18 cannot be pushed in any longer if the
plug housings 15 and 24 of the backplane side and the package side
optical connector plugs 14 and 23 come in contact with each other
before the unlatching part 20 at the third housing 18 side
unlatches the latching pawl 10 from the latching projection 4.
Consequently, the latched connection between the first and second
housings 3 and 7 cannot be unlatched, so that the first housing 3
receives the force of pushing the third housing 18 down and this
pushing-down force affects the backplane 1 via the first housing 3,
causing a problem that the characteristics of the electric and
optical circuits of the backplane 1 are degraded. In order to solve
this problem, this embodiment provides the backplane connector with
a configuration for unlatching the latched connection between the
first housing 3 and the second housing 7 completely before the plug
housing 15 comes in contact with the plug housing 24 when the third
housing 18 is pressed down in the connecting direction.
This is why the slope provided on the outer surface of the latching
pawl 10 is formed as a two-shoulder stepped one (package side slope
12 and tip side slope 13) in this embodiment as described above.
And, if d is defined as the overlapping area of the latched
connection between the latching projection 4 and the engaging
stepped portion 11 of the latching pawl 10, .DELTA. is defined as
the interval between the plug housings 15 and 24 at the backplane 1
side and the package 2 side when the third housing 18 is fit in the
first housing 3, .theta..sub.2 is defined as the base end side
inclination of the latching pawl 10, and .theta..sub.1 is defined
as the tip side inclination, then .theta..sub.1 and .theta..sub.2
are set to satisfy the relationship in the following expression
(1).
In other words, if, when the latching projection 4 is engaged
latchingly with the latching pawl 10, the overlapping area of the
latching engagement is defined as d and the tip side inclination of
the latching pawl 10 is defined as .theta..sub.1, then the
inserting length of the third housing 18, needed until the latched
connection is unlatched after the unlatching part 20 comes in
contact with the tip side slope 13 of the latching pawl 10, is
represented as d/tan .theta..sub.1 (0<.theta..sub.1
<90.degree.).
Furthermore, since the plug housings 15 and 24 are unlatched before
they come in contact with each other, the condition of d/tan
.theta..sub.1 <.DELTA. must be satisfied.
In other words, the relationship of .theta..sub.1 >arc tan
(d/.DELTA.) must be satisfied.
The value of .DELTA. is about 0.4 to 0.8 mm for a multi-fiber
optical connector plug. The value of d is 0.5 to 0.7 mm, but when
in .DELTA.=0.4 mm, the result becomes .theta..sub.1
>60.degree..
On the other hand, when the package 2 is removed, that is, when the
housing 18 is pulled out in the disconnecting direction, the force
of latching the first housing 3 to the second housing 7 again is
proportional to sin .theta..sub.2 (0<.theta..sub.2
<90.degree.) if the inclination of the base end side slope 12 of
the latching pawl 10 is .theta..sub.2. Consequently, the larger the
.theta..sub.2 value becomes, the larger the latched reconnection
force becomes. And, when this reconnection force becomes large,
more force is needed to pull the third housing 18 out, so that it
becomes difficult to connect and disconnect the package 2. This is
unfavorable. Thus, connecting and disconnecting the package 2 must
be done with a less force, and it should preferably satisfy the
relationship of .theta..sub.2 <45.degree..
Consequently, the above expression (1) must be satisfied and this
embodiment is designed to satisfy the relationship represented in
the expression (1). Especially, in the case of .DELTA.=0.4 mm and
d=0.7 mm, the relationship of 0<.theta..sub.2
<60.degree.<.theta..sub.1 <.theta.90.degree. should
preferably be satisfied.
Since the latching pawl 10 has a two-shoulder stepped slope of
.theta..sub.1 and .theta..sub.2 in this embodiment and the tip side
slope 13 of the latching pawl 10 is given a larger inclination
.theta..sub.1, the latching connection between the first housing 3
and the second housing 7 can be unlatched and disconnected
completely with a less inserting length of the third housing 18. In
addition, since the base end side slope 12 of the latching pawl 10
is given a smaller inclination .theta..sub.2, the first housing 3
can be latched and connected to the second housing 7 again with a
less force when the package 2 is disconnected from the backplane
connector, and the package 2 can be disconnected with a less
force.
However, if the material strength of the ferrules 16 and 25 of the
backplane side optical connector plugs 14 and the package side
optical connector plugs 23 are weaker than those of the alignment
pins 31, for example, if the ferrules 16 and 25 are made of plastic
and the alignment pins 31 are made of metal or ceramics, the
alignment pin 31 fixed to one of the optical connector plugs, that
is, to the backplane side optical connector plug in this
embodiment, must be sized so as to be fit surely in the alignment
holes 30 of the package side optical connector plug ferrule 25.
In an optical connector plug, if, when the protrusion length from
the plug housing 15 at the tip of the ferrule 16 is defined as f
and the protrusion length of the alignment pins 31 from the end
face of the ferrule 16 is defined as a, the inclination between the
plug housings 15 and 24 is only .alpha. when the alignment pins 31
are fit in the alignment holes 30 after the second housing 7 begins
to be fit in the third housing 18, then the alignment pins 31 are
deviated from their due positions by tan .alpha..times.(f+a) due to
this inclination. This inclination .alpha. is decided by the
clearance .delta.h formed after the fitting between the second
housing 7 and the third housing 18 and the value of fitting length
L=L.sub.0 -a between these second and third housings 7 and 18. This
L.sub.0 is decided by the length in the fitting direction of the
second and third housings 7 and 18. In other words, the positional
deviation of the alignment pins 31 is represented by an expression
of {.delta.h/(L.sub.0 -a)}.times.(f+a).
The relative positional deviation between the second and third
housings 7 and 18 is .delta.h/2.
If the difference between the diameter of the alignment holes 30
and the tip diameter of the alignment pins 31 is assumed to be a
.delta..phi., the relationship in the expression (2) must thus be
satisfied to fit the alignment pins 31 in the alignment holes
30.
This embodiment is designed to satisfy the relationship in this
expression (2).
Usually, the .delta..phi. size takes a value of 0.4 mm to 0.7 mm
for manufacturing backplane connectors. The smaller the .delta.h
value is, the more the positional deviation is reduced, but when
manufacturing errors are taken into consideration, an error of
about 0.1 mm will be neglectable. The f and a values are 0.9 to 1.1
mm and 1.6 to 3.3 mm respectively for standard multi-fiber optical
connector plugs.
When those sizes are taken into consideration and, for example,
alignment pins (.delta..phi.=0.7 mm) are used, the relationship of
L.sub.0 >4 mm must be satisfied as the fitting length between
the second and third housings 7 and 18. If single-fiber optical
connector plugs are used integrally for the second and third
housings, the second housing 7 is arranged in a position about 3 mm
deeper than the first housing 3. At this time, the L0 length will
be about 2 mm. (However, in the case of a single-fiber optical
connector plug, no alignment pin 31 is used. Thus, the fitting
length can be longer by the length of the alignment pin 31 when the
axial alignment is made between the ferrules of the backplane side
optical connector plug and the package side optical connector
plug.)
In the case of a backplane connector having a multi-fiber optical
connector plug housed in the second and third housings 7 and 18
respectively just like that of this embodiment, the second housing
is extended in the fitting direction to obtain L.sub.0 =4 mm. In
other words, the second housing is arranged at a position about 1
mm deeper than the first housing 3. At this time, the latching pawl
10 of the second housing 7 must be prevented from coming in contact
with the body of the second housing 7 (outer surface of the second
housing) as shown in FIG. 9 when the first housing 3 is unlatched
and disconnected from the second housing 7. As shown in FIG. 10,
therefore, an escaping recess 32 must be formed on the outer
surface of the second housing 7, so that the recess 32 can prevent
the latching pawl 10 from coming into contact with the outer
surface of the second housing 7.
Furthermore, in this embodiment, the fixing force of the alignment
pins 31 is set enough to prevent the alignment pins 31 from being
released from the alignment holes on the backplane optical
connector plug when the backplane connector is disconnected. The
alignment pins 31 are fixed on the backplane optical connector plug
14 side in this embodiment. More concretely, a part 33 as shown
with an alternate long and short dash line in FIG. 3 is provided at
the rear end side of the ferrule 16 to clamp the alignment pins 31
made of metal, ceramics, etc. The clamping part 33 is incorporated
in the plug housing 15. And, the base end side of those two
alignment pins 31 is clamped or bonded to this part 33. The force
of fixing the alignment pins 31 is defined as F.sub.1. If, when the
backplane connector is connected, the package 2 is removed, then
the third housing 18 receives a force in the pulling-out direction.
The removing force at this time is defined as F.sub.2.
This removing force is a force needed to latch and connect the
first housing 3 to the second housing 7 again and to disconnect the
first housing 3 from the third housing 18. When the latching
projection 4 is latched and connected to the latching pawl 10 again
to unlatch the locked connection between the locking latch 5 and
the locking pawl 22 of the first and third housings 3 and 18 and
disconnect the backplane connector, if a fitting deviation or an
inclination occurs between the first housing 3 and the third
housing 18, then the removing force of the third housing 18 works
on the alignment pins 31, so that the alignment pins 31 are pulled
out. In order to prevent the alignment pins 31 from being pulled
out with the removing force, the fixing force F.sub.1 of the
alignment pins 31 must be kept larger than the removing force
F.sub.2 working when the third housing 18 is removed. With this, it
is possible to prevent the alignment pins 31 from being released.
Such the point is taken into consideration in this embodiment to
set the fixing force F.sub.1 of the alignment pins 31 larger than
the removing force F.sub.2.
In this embodiment, a fixing force of 1 to 2 kg is given for fixing
the alignment pins 31 and the inventor has recognized that the
removing force F.sub.2 of the third housing is about 600 to 800 g
through tests when the third housing is made of, for example, a
plastic material such as PBT, PPS, etc. Thus, the above condition
F.sub.1 >F.sub.2 can be satisfied enough.
The present invention is not limited only to the above embodiment,
but the embodiment may be varied in various ways. For example,
although the alignment pins 31 are fixed to the backplane side
optical connector plug 14 in the above embodiment, the alignment
pins 31 may be fixed to the package side optical connector
plug.
Furthermore, although a multi-fiber optical connector plug is
incorporated in the second and third housings 7 and 18 respectively
in this embodiment, a single-fiber optical connector plug may be
incorporated in those housings 7 and 18 respectively. When this
single-fiber optical connector plug is incorporated, the alignment
holes 30 and the alignment pins 31 may be omissible.
Furthermore, a plurality of optical connector plugs may be
incorporated in the second and third housings 7 and 8 respectively.
When a plurality of optical connector plugs are incorporated such
way and a multi-fiber type optical connector plug is adopted as
each of such the optical connector plugs, it is possible to realize
a high density packing of optical fibers.
* * * * *